Voicemail systems allow a calling party to leave a voicemail message for a called party if the called party is unavailable to answer an incoming call. Typically, a calling party places a call to a desired called party using a landline or wireless telephone and, after a predetermined number of unanswered rings, the host network routes the call to a voicemail system that includes a voicemail box for the called party. The voicemail system plays a default or custom greeting that prompts the calling party to leave a voicemail message. The voicemail message is recorded and stored in association with the called party's voicemail box for retrieval by the called party.
Traditional voicemail systems (referred to herein as plain-old voicemail or POVM systems) allow users to retrieve messages stored in his or her voicemail box using a telephone user interface (TUI). Users are able to listen to messages, skip messages, delete messages, and save messages using the TUI. TUIs also provide functions for users to set a voicemail greeting, record a voicemail greeting, record a name, and set/change a voicemail password.
Other voicemail systems allow a user to access voicemail messages directly from their mobile device without having to call a voicemail system. Such systems are commonly referred to as visual voicemail (VVM) systems. In these systems, a calling party leaves a voicemail message in a typical manner as described above. The VVM system then sends the voicemail message in an appropriate audio file format to the user's mobile device for storage and retrieval. Alternatively, the VVM system sends header information including, for example, the calling party, length of the voicemail message, the date and time the voicemail message was recorded, and any necessary details regarding the host VVM system that the mobile device needs to retrieve the voicemail message. When the called party selects the voicemail message from the mobile device, the mobile device uses the header information to contact the VVM system and request the voicemail audio content associated with the voicemail message. The VVM system sends the voicemail audio content in an appropriate audio file format to the mobile device. The VVM system may alternatively stream the voicemail audio content to the mobile device.
When the user travels to a different country or within the same country with their mobile device, the user's home network may not have coverage in the visited area. Carriers often establish roaming agreements with foreign carriers so that their subscribers are still able to make and receive calls while roaming onto another carrier's network (foreign network), in the visited area. A foreign network, therefore, may be in another country, requiring international roaming, or may be a network operated by another carrier in the same country, requiring domestic roaming.
When a subscriber powers on their mobile device in the visited area, the mobile device receives radio signals from one or more foreign networks operating in that area. After one of the foreign networks is selected by the mobile device, the carrier of the selected network authenticates the user's mobile device with the user's home carrier including, for example, determining whether the user is a valid user with roaming capability enabled for their account. If the home carrier responds with a positive authentication, the user is permitted to use his or her mobile device on the foreign carrier network. For billing, the foreign carrier will keep a record of all calls and other activity from the user's mobile device and send the record along with the corresponding charges to the user's home carrier. The home carrier aggregates these charges for billing to the user.
At present, when a mobile device is configured for VVM service and the mobile device is roaming, the mobile device may lose access to VVM service due to data connectivity being unavailable in the foreign network. VVM service may also be inaccessible due to network incompatibilities or VVM interoperability equipment being unavailable between the foreign and home networks.
In these situations, for example, if a user receives a voicemail message, the voicemail system cannot send the voicemail message to the user's mobile device. As such, the user must call-in to the voicemail system to check whether a voicemail message has been deposited. The only indication to the user that a voicemail message may have been deposited is the presence of a missed call notification on his or her mobile device. This can lead to missed voicemail messages if the user does not actively check the voicemail system each time a call is missed. This can also lead to increased network traffic due to users having to constantly check the voicemail system for new voicemail messages. The increased network traffic can also lead to undesirable roaming charges for calls to the voicemail system.